12 



Universal Time (UTC). For the 1996 WLIS survey, data from NOAA tide station 8467150 

 in Bridgeport Harbor, Bridgeport, CT was used for tidal calculations. The NOAA 6-minute 

 tide data were downloaded in the MLLW datum, corrected to local time, and tidal 

 differences based on Greens Ledge, Sheffield Island, Connecticut, were applied. 



In order to make valid comparisons between present and past bathymetric surveys of 

 the area, the July 1992 and June 1990 bathymetry models were recorrected to observed 

 MLLW. The OLLD database also provides historic NOAA observed tidal data 

 (31 December 1993 and earlier) as hourly water heights. Through interpolation, a smooth 

 tidal curve was developed to allow for accurate tidal corrections of historic bathymetric 

 data sets. 



A Seabird Instruments, Inc. SEACAT SBE 19-01 Conductivity, Temperature, and 

 Depth (CTD) probe was used to obtain sound velocity measurements at the start, midpoint, 

 and end of each survey day. The data collected by the CTD probe were bin-averaged to 1 

 meter depth intervals to account for the pycnocline (a rapid change in density that creates 

 distinct layers within the water column). A mean sound velocity was then calculated using 

 the bin-averaged values. 



The bathymetric data were analyzed using SAIC's Hydrographic Data Analysis 

 System (HDAS), version 1.03. Raw bathymetric data were imported into HDAS, 

 corrected for sound velocity, and standardized to Mean Lower Low Water using the 

 NOAA observed tides. The bathymetric data were then used to construct depth models of 

 the surveyed area. A detailed discussion of the bathymetric analysis technique is provided 

 in the DAMOS Navigation and Bathymetry Standard Operating Procedures (Murray and 

 Selvitelli 1996). 



2.5 REMOTS® Sediment-Profile Photography 



REMOTS® photography was used to detect the distribution of dredged material 

 layers, map benthic disturbance gradients, and monitor the benthic infaunal recolonization 

 and successional stams of the H mound and the I mound, as well as the WLIS reference 

 areas. Cross-sectional photographs of the top 20 cm of sediment were taken for analysis 

 and intercomparison with the ambient sediments of the adjacent WLIS reference areas 

 (SOUTH and SW-REF). The Rhoads and Germano (1982, 1986) protocol for REMOTS® 

 analysis was followed for measurements and interpretation. 



Three replicate photographs were taken at 13 stations over the WLIS H and WLIS I 

 mounds (Figure 2-4, Appendix A Table 1). The REMOTS® sampling grids formed a 

 cross-shaped pattern with three stations along each of four arms and one station in the 



Monitoring Cruise at the WLIS Disposal Site, September 1997 and March 1998 



